We often take sight for granted, but it merits a closer look. As this infographic shows, there's more to our vision than meets the eye.

Why do we blink? Why do we have two eyes instead of one? And why do we have eyebrows at all?

Humans rely heavily on sight, yet we tend to overlook the amazing organs that make it possible. To help the humble eyeball get its moment in the sun — with UV protection, of course — MNN offers this two-part guide to human vision. Part 1 focuses on eyes' inner workings and how they show us the world, while Part 2 explores eye color, vision enhancement, ocular emotion and more. If you're interested in eyes, look no further.